The present invention relates to a photographic camera and a method for initially advancing photographic film in the camera, and more particularly to a film initial advance apparatus and method for a camera in which rotation of a spool of a film cassette causes a film leader to advance out of the film cassette.
There are known 35 mm self-advancing film cassettes which have a film leader that does not protrude from the cassette shell but rather is contained therein, as disclosed in U.S. Pat. Nos. 4,832,275, 4,834,306 and 4,846,418, for example. Rotation of a spool, in an unwinding direction of the photographic film by a film feeding mechanism causes the film leader to advance outside of the cassette shell through a film passageway of the film cassette. In order to prevent the roll of photographic film wound on the spool from loosening, there are provided flanges on the spool or ridges inside the cassette shell.
A camera suitable for using the self-advancing film cassette as described above is disclosed in U.S. Pat. No. 4,855,773, and Japanese Patent Laid-open Publications Nos. 2-113230 and 2-67534. The film feeding mechanism incorporated in such a camera rotates a fork for transporting the photographic film in a normal or unwinding direction and a reverse or rewinding U.S. Pat. No. 4,860,041, for example, the fork is rotated in the normal direction when the back lid is closed so as to advance the film until the first frame is positioned on an exposure aperture of the camera.
In such a film cassette, however, the film roll might be loosely wound around the spool, which will increase the pressure or friction between the outer surface of the film roll and the ridges or inner surface of the flanges. Such a high pressure or friction between the outer surface of the film roll and the ridges or inner surface of the flanges may cause the film to jam when trying to advance the film leader to the outside of the film cassette by rotating the spool. That is, the film leader might be stopped on an inner surface of the cassette shell due to the high contact pressure or friction to cause the film to jam. Using a larger force to rotate the fork may serve to prevent the film from jamming, but necessitates a stronger motor in the camera which increases the cost of the camera. In addition, the film feeding mechanism must be made from a stronger material, which will increase the cost of the camera.